1. Field of the Invention
This invention pertains to remote controls, and more particularly to apparatus and methods for actuating electrical circuits at one location in response to human activities at a different location.
2. Description of the Prior Art
It is well known to control an electrical device located inside an enclosure from outside of the enclosure. Examples include electrically powered exhibits at museums or the like. Such exhibits are usually actuated by a person who manually pushes a button on the outside of a case that houses the exhibit. Another example, in which the enclosure is a house, is the ubiquitous doorbell. The foregoing, of course, are merely representative of a wide variety of remote control systems that utilize physical connections, e.g., buttons and wires, between the person and the activated device.
It is also well known to employ motion detectors to activate electrical devices in response to movements at locations remote from the devices. In a motion detector, there is no physical connection between a person who trips the detector and the activated electrical device. Rather, motion detectors invariably work on the principal of infrared light. A sensor unit emits a beam of infrared light, which is directed to a stationary reflector at some distance from the sensor. The reflector reflects the beam back to the sensor. The sensor is wired to control an electrical device such as a lamp or audio signal.
As long as the emitted beam is reflected back to the sensor, the electrical device remains in a deactivated state. However, if an opaque object, such as a part of a person's body, is placed between the infrared sensor and the reflector, the emitted beam is not received back at the sensor. In that case, the sensor operates to activate the electrical device. Common applications of light based motion detectors are burglar alarms and photoelectric eye door openers.
Despite the numerous types of remote control systems presently available, there nevertheless is room for new developments to them.